An elevator comprises an elevator car moving in a first direction upwards and downwards in an elevator shaft. The elevator car transports people and/or goods between the landings in a building. The elevator car is supported by a car sling comprising a horizontal upper transom, a horizontal lower transom and vertical side frames connecting the ends of the upper transom and the lower transom. There are further guide rails being attached to the wall structure of the elevator shaft and extending vertically along the height of the elevator shaft. The car sling is guided with gliding means on the guide rails. The car is thus guided in the lateral direction with the gliding means gliding on the guide rails when moving up and down in the elevator shaft.
The horizontal cross-section of the guide rails has the form of a letter T. The horizontal branch of the letter T is attached to support means being attached to the wall structure of the elevator shaft. The vertical branch of the letter T forms three gliding surfaces for the gliding means. There are thus two opposite side gliding surfaces and one front gliding surface in the guide rail. The gliding means comprises a frame part and a gliding part. The horizontal cross-section of the gliding part has the form of a letter U so that the inner surface of the gliding part sets against the three gliding surfaces of the guide rail. The horizontal cross section of the frame part has also a U-shaped section surrounding the gliding part on three sides. The frame part comprises further outwardly extending flanges at the bottom of the letter U for attaching the gliding means to the vertical side frame of the car sling. There are elasticity means between the gliding part and the frame part in order to isolate the gliding part from the frame part.
The guide rails are formed of rail elements of a certain length. The rail elements are connected in the installation phase end-on-end one after the other. It is almost impossible to install the guide rails so that they would form a fully straight line along the whole height of the elevator shaft. The inevitable small deviations in the straightness of the guide rail will result in lateral forces acting on the gliding means when the car moves upwards and downwards in the shaft. These lateral forces will cause vibrations acting on the gliding means and thereby also acting on the car. The vibrations acting on the car will also cause noise disturbing the passengers in the car. The elasticity means between the gliding part and the frame part in the gliding means absorb the vibrations and prevent the vibrations from progressing to the car.
WO 2011/070237 discloses gliding means of an elevator. The gliding means comprises a frame part, a gliding part and an elastic insulation part between the frame part and the gliding part. The elastic insulation part insulates the elevator car from the guide rail.
US 2010/0065382 discloses gliding means comprising a gliding part for an elevator. The gliding means comprises further a first bracket connected to the gliding part and a second bracket connected to the car. There are further a plurality of elongated elastomeric members arranged generally from a first end of the gliding means to a second end of the gliding means and connected between the first bracket and the second bracket. The gliding part and the first bracket are substantially surrounded on three sides by the second bracket. Each of the plurality of elongated elastomeric members is configured for deflection under loads of increasing magnitude.
The flexible support achieved with the elasticity means between the gliding part and the frame part of the gliding means is, however, problematic during the installation of the car sling. The gliding means is attached to the upper portion and the lower portion of the side frame of the car sling. The side frames are then positioned against the guide rail so that the gliding part of the gliding means sets against the guide rail. The side frames of the car sling are kept in place during the installation of the lower transom, the car and the upper transom by compression with a G-clamp positioned at the lower end of the side frames. The compression of the G-clamp will result in that the lower gliding means is pressed toward the guide rail due to the elasticity means between the glide part and the frame part. This will result in that the side frame will become inclined.
There are also prior art flexible gliding means containing screws at the back of the gliding means for restraining the rubber isolation between the gliding part and the frame part during installation of the car sling. The screws in these prior art gliding means need to be adjusted after the installation of the car sling in order to retain the flexibility of the rubber isolation. The screws help to keep the vertical side frames of the car sling in a vertical position during installation of the frame. The screws do not, however, eliminate the need to adjust the recommended 0.5 to 1 mm gap between the gliding surface of the gliding means and the guide rail after the car sling and the car has been installed.